Nanoimprint resist, nanoimprint mold and nanoimprint lithography

ABSTRACT

A nanoimprint resist that includes a hyperbranched polyurethane oligomer (HP), a perfluoropolyether (PFPE), a methylmethacrylate (MMA), a diluent solvent and a photo initiator. A method of a nanoimprint lithography is also provided.

RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 12/712,178, filed Feb. 24, 2010 entitled“NANOIMPRINT RESIST, NANOIMPRINT MOLD AND NANOIMPRINT LITHOGRAPHY” thedisclosure of which is incorporated by reference.

BACKGROUND

1. Technical Field

This disclosure relates to nanoimprint resist, nanoimprint mold andnanoimprint lithography.

2. Description of Related Art

In fabrication of semiconductor integrated electrical circuits,integrated optical, magnetic, mechanical circuits and micro devices, andthe like, are some of the key processing methods is the lithography.Lithography creates a pattern in a thin film located on a substrate, sothat, in subsequent process steps, the pattern will be replicated in thesubstrate or in another material located on the substrate. Since therole of the thin film is to protect a part of the substrate in thesubsequent replication steps, the thin film is called resist.

Nanoimprint lithography (NIL) is a method of fabricating nanometer scalepatterns. It is a simple nanolithography process with low cost, highthroughput and high resolution. It creates patterns by mechanicaldeformation of imprint resist and subsequent processes. The imprintresist is typically a monomer or polymer formulation that is cured byheat or UV light during the imprinting. Adhesion between the resist andthe template is controlled to allow proper release. There are manydifferent types of nanoimprint lithography, including thermoplasticnanoimprint lithography and photo nanoimprint lithography.

Thermoplastic nanoimprint lithography (T-NIL) is the earliestnanoimprint lithography developed by Prof. Stephen Chou's group. In astandard T-NIL process, a thin layer of imprint resist (thermoplasticpolymer) is spin coated onto the sample substrate. Then the mold, whichhas predefined topological patterns, and the sample are pressed togetherunder a certain pressure. When heated up above the glass transitiontemperature of the polymer, the pattern on the mold is pressed into thesoftened polymer film. After being cooled down, the mold is separatedfrom the sample and the pattern resist is left on the substrate. Apattern transfer process (e.g. reactive ion etching) can be used totransfer the pattern in the resist to the underneath substrate.

In photo nanoimprint lithography (P-NIL), a photo (UV) curable liquidresist is applied to the sample substrate and the mold is normally madeof transparent material (e.g. fused silica). After the mold and thesubstrate are pressed together, the resist is cured in UV light andbecomes solid. After mold separation, a similar pattern transfer processcan be used to transfer the pattern in resist onto the underneathmaterial.

However, the central goals in today's nanoimprint lithography are tomake NIL appropriate to mass-productions for improving NIL performanceand yield. Modification of raw materials referred to as mold materialand resist. As far as the resist, lithography generally employed it asmask of different processes, because of it properties of thermalplastic, UV curing and easy removal such as PMMA, PS, and HSQ and so on.Otherwise, due to the resist's low modulus, poor solvent resistance, andhigh thermal expansion coefficient and uneasily patterned, thesedisadvantages lead to distortions and deformations of the residentimprinting nanostructures. As far as the materials for mold, quartz andSi or SiO2 wafer were usually applied, while this kind of mold generallyfabricated by electronic beam lithography (EBL), it is easily crushedunder high pressure.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the embodiments can be better understood with referencesto the following drawings. The components in the drawings are notnecessarily drawn to scale, the emphasis instead being placed uponclearly illustrating the principles of the embodiments. Moreover, in thedrawings, like reference numerals designate corresponding partsthroughout the several views.

FIG. 1 is a schematic structural view of one embodiment of a flexiblenanoimprint mold.

FIG. 2 is a schematic structural view of one embodiment of a flexiblenanoimprint mold.

FIGS. 3A through 3C are sectional views of one embodiment of a methodfor manufacturing the flexible nanoimprint mold shown in FIG. 1.

FIGS. 4A through 4D are sectional views of one embodiment of a methodfor manufacturing the flexible nanoimprint mold shown in FIG. 1.

FIGS. 5A through 5G are sectional views of one embodiment of a method ofNanoimprint lithography (NIL).

FIGS. 6A through 6D are sectional views of one embodiment of a method ofNIL.

FIGS. 7A through 7G are sectional views of one embodiment of a method ofNIL.

DETAILED DESCRIPTION

The disclosure is illustrated by way of example and not by way oflimitation in the figures of the accompanying drawings in which likereferences indicate similar elements. It should be noted that referencesto “an” or “one” embodiment in this disclosure are not necessarily tothe same embodiment, and such references mean at least one.

Nanoimprint Resist

A nanoimprint resist of one embodiment of includes a hyperbranchedpolyurethane oligomer (HP), a perfluoropolyether (PFPE), amethylmethacrylate (MMA), and a diluent solvent. In the nanoimprintresist, the weight percent (wt %) of the HP is in a range from about 50wt % to about 60 wt %. The wt % of the PFPE is in a range from about 3wt % to about 5 wt %. The wt % of the MMA is in a range from about 5 wt% to about 10 wt %. The wt % of the diluents solvent is in a range fromabout 25 wt % to about 35 wt %.

The chemical structure of the PFPE is

wherein m:n is in a range from about 0.6 to about 1.

If the nanoimprint resist is used in T-NIL, the HP can be formed by acopolymerization of the trimellitic anhydride, ethylene glycol, epoxyacrylic acid copolymer, or can also be formed by a ring-openingcopolymerization of epoxy acrylic acid and ethylene mercaptan. Thechemical structure of the HP is

If the nanoimprint resist is used in P-NIL, the HP can be formed by acopolymerization of trimellitic anhydride, ethylene mercaptan, and epoxyacrylic acid, or can also be formed by a ring-opening copolymerizationepoxy acrylic acid and ethylene glycol. In one embodiment, the chemicalstructure of the HP is

The diluent solvent can be 2-hydroxyethyl methacrylate or 2-HydroxyEthyl 2-methyl ethylene. The nanoimprint resist can further includepolydimethlsiloxanes (PDMS) or methacrylatesilane with a wt % in a rangefrom about 5% to about 10%, to enhance the adhesion between thesubstrate and the nanoimprint resist. The nanoimprint resist may includean initiator with a wt % in a range from about 0.1% to about 2%. Theinitiator can be thermal initiator or photo initiator, thus thenanoimprint resist can be heat cured or photo cured. In one embodiment,a chemical structure of the photo initiator is

The nanoimprint resist can be made by the method of mixing HP, with wt %ranging from about 50 wt % to about 60 wt %, PFPE, with wt % rangingfrom about 3 wt % to about 5 wt %, MMA, with wt % ranging from about 5wt % to about 10 wt %, diluent solvent, with wt % ranging from about 25wt % to about 35 wt %, and initiator, with wt % ranging from about 0.1wt % to about 2 wt %, standing for about 1 hour to 3 hours to form amixture, and filtering the mixture through a 0.2 μm syringe filter aftermixing for more than 2 hours to form a nanoimprint resist as a uniformliquid resin.

It is also understood that polydimethlsiloxanes (PDMS) ormethacrylatesilane with a wt % in a range from about 5% to about 10% canbe added in the mixture to enhance the adhesion between a substrate andthe nanoimprint resist when the nanoimprint resist is in use.

Sufficient low surface energy and high modulus are the two criticalfactors for NIL. In the nanoimprint resist described-above, themacromolecular chain of —(CF₂CF₂—O)_(m)—(CF₂—O)_(n)— of PFPE containedperfluoropolyether and donates the facile surface energy. The crosslinking polymerization is taken place among CH₂═C(CH₃)COO— of PFPE,epoxy terminal groups of HP and the diluters. Broadly cross-linkingamong these regents is facilitated to solidify the Young's modulus ofcomposition. Thus, the nanoimprint resist described-above have highmodulus, rich solvent resistance, low thermal expansion coefficient andare easily patterned.

Flexible Nanoimprint Mold

Referring to FIG. 1, a flexible nanoimprint mold 100 of one embodimentused in NIL includes a flexible body 10 and a molding layer 105 formedon a flexible body 10. The molding layer 105 includes a plurality ofprotrusions 104 having a desired shape and a recess 106 defined betweenadjacent protrusions 104. The plurality of protrusions 104 and recesses106 cooperatively form a nanopattern 108.

The flexible body 10 can be a flat plate. The shape and size of theflexible body 10 is not limited and can be prepared according to actualneeds. The flexible body 10 can be made of flexible transparent polymermaterials, such as silicone rubber, polyurethane, epoxy resin, polymethyl methacrylate, and polyethylene terephthalate (PET). In oneembodiment, the flexible body 10 is a square flat plate with a diameterof 4 inches made of PET.

A width of the plurality of protrusions 104 and recesses 106 can be in arange from about 50 nanometers to about 200 nanometers. The moldinglayer 105 is a polymer material formed via a cross linkingpolymerization of the nanoimprint resist used in the photo nanoimprintlithography (P-NIL). The nanoimprint resist used in the P-NIL isdescribed above in detail.

The macromolecular chain of —(CF₂CF₂—O)_(m)—(CF₂—O)_(n)— of PFPEcontains perfluoropolyether and donates the facile surface energy. Thecross linking polymerization may take place among CH₂═C(CH₃)COO— ofPFPE, epoxy terminal groups of HP and the diluters. Broadlycross-linking among these regents may facilitate to solidify the Young'smodulus of the molding layer 105. Sufficient low surface energy and highmodulus are two important factors for NIL. The former contributes toeasily releasing, the later keep the nanopattern 108 durable, and bothof them render that the flexible mold 100 could keep the primalmorphology without defects and contamination for long time utilizing.

Referring to FIG. 2, the flexible nanoimprint mold 100 can furtherinclude an adhesive layer 103 located between the molding layer 105 andthe flexible body 10. Thus the adhesion between the molding layer 105and the flexible body 10 can be enhanced. In one embodiment, theadhesive layer 103 is made of methacrylatesilane.

Referring to FIGS. 3A to 3C, a method of one embodiment for making theflexible nanoimprint mold 100 includes:

(S11) providing a flexible body 10, depositing a polymer compound 110 onthe flexible body 10;

(S12) providing a master stamp 20 having a nanopattern 208, pressing thenanopattern 208 into the polymer compound 110 of the flexible body 10;and

(S13) curing the polymer compound 110, separating the master stamp 20from the flexible body 10 to form a molding layer 105 on the flexiblebody 10.

In step (S11), the polymer compound 110 can be the nanoimprint resistused in P-NIL. The polymer compound 110 can be formed on the flexiblebody 10 through any appropriate technique such as screen printing andspin casting. The polymer compound 110 has a thickness ranging fromabout 100 nanometers to about 300 nanometers. In one embodiment, thepolymer compound 110 is formed via spin casting. The spin-coating speedis in a range from about 5400 Round Per minute (RPM) to about 7000 RPM,the time is from about 0.5 minutes to about 1.5 minutes. The polymercompound 110 can be baked about 3 to 5 minutes at a temperature of about140° C. to about 180° C.

In some embodiments, an adhesive layer 103 can be deposited on theflexible body 10 before forming the polymer compound 110 via spincasting. The polymer compound 110 is deposited on the adhesive layer103. Thus the adhesion between the flexible body 10 and the polymercompound 110 can be enhanced. In one embodiment, the adhesive layer 103is made of methacrylatesilane.

In step (S12), the master stamp 20 includes a plurality of projectingportions 24 and a plurality of gaps 26. One gap 26 is defined betweenadjacent projecting portions 24. The plurality of projecting portions 24and gaps 26 forms a nanopattern 208. The master stamp 20 can be atransparent rigid material, such as silicon dioxide, silicon, quartz,and glass diboride, to be hard relative to the polymer compound 110. Themaster stamp 20 can be patterned with the projecting portions 24 andgaps 26, using electron beam lithography, reactive ion etching (RIE) andother appropriate methods. A depth of projecting portions 24 can be in arange from about 5 nm to about 200 nm, depending upon the desiredlateral dimension. A width of the gaps 26 and the projecting portions 24can be in a range from about 50 nanometers to about 200 nanometers. Inone experiment, the master stamp 20 is made of quartz.

In one embodiment, the master stamp 20 is fabricated using electron beamlithography (EBL), metal lift-off and then dry reactive ion etching(RIE) processes. Nanoscale patterns of about 50 nm×200 nm pitch areformed in a ZEP520A resist on the quartz samples using EBL. Typical EBLprocesses are carried out beam energy of 100 keV, beam current of about200 pA, and cold development in ZED-N50. After the development ofZEP520A patterns, 40 nm thick Cr is evaporated on the sample and alift-off process is performed in butanone in an ultrasonic bath forabout 5 min to transfer the ZEP520A patterns to the Cr layer. Using theCr gratings as a mask, reactive ion etching using pure CF₄ is performedwith power of 40 W, 2 Pa, CF₄ 40 sccm. After the Cr residual is strippedaway, the patterned quartz works as the master stamp 20.

Referring to FIG. 3B, in step (S12), the master stamp 20 can be pressedinto the polymer compound 110 to form a plurality of recesses 106 in thepolymer compound 110. Each recess 106 corresponds to one projectingportion 24 of the master stamp 20. Step (S12) can be performed in avacuum environment to make the polymer compound 110 can be fully filledinto the entire gaps 26 of the master stamp 20. In one embodiment shownin FIGS. 3A-3C, projecting portions 24 are not pressed all of the wayinto the polymer compound 110 and do not contact the flexible body 10.

In step (S13), the polymer compound 110 is cured via UV light andbecomes solid. In one embodiment, UV curing step is carried out on theconditions of 17 mJ*cm⁻² and 10 seconds (sec). After peeling of themaster stamp 20 from the flexible body 10, the molding layer 105 isformed on the flexible body 10. The molding layer 105 includes aplurality of protrusions 104 and recesses 106. Each protrusion 104corresponds to one gap 26 of the master stamp 20. The recesses 106 formreliefs which conform generally to the shape of the projecting portions24 of the master stamp 20. The plurality of protrusions 104 and recesses106 form the nanopattern 108.

Referring to FIGS. 4A to 4D, a method of one embodiment for making theflexible nanoimprint mold 100 includes:

(S21) providing a master stamp 20 having a nanopattern 208 and aflexible body 10;

(S22) depositing a polymer compound 110 to cover the nanopattern 208;

(S23) applying the flexible body 10 to the polymer compound 110 andcompressing the flexible body 10 and the master stamp 20; and

(S24) curing the polymer compound 110, separating the flexible body 10and the master stamp 20 to form a molding layer 105 on the flexible body10.

In step (S22), before depositing the polymer compound 110, the masterstamp 20 can be pretreated by immersing the master stamp 20 in a piranhasolution for about 30 min, and self-assembling a fluorinated monolayermolecular membrane of F13-TDS under 250° C. for about 30 min and rinsingwith hexane as needed. Step (S22) can be performed in a vacuumenvironment to make the polymer compound 110 can be fully filled in theentire gaps 26 of the master stamp 20.

In step (S23), an adhesive layer 103 can be deposited on the flexiblebody 10 before applying the flexible body 10 to the polymer compound110, to enhance the adhesion between the flexible body 10 and polymercompound 110. In one embodiment, the adhesive layer 103 is made ofmethacrylatesilane.

The flexible nanoimprint mold 100 employ HPFPE as flexible moldmaterials. Hyperbranched polymer (HP) is applied to intermediate PFPE toachieve the HPFPE with enough viscosity, low surface energy, modulus andstability. In which, the backbone of fluorinated polyether with—(CF₂CF₂O)_(m)—(CF₂O)_(n)— generates low surface energy for NILreleasing. The ending groups acrylic structures CH₂═C(CH₃)COO— of PFPEmay produce the modulus by cross-linking itself with epoxy groups of HPoligomer, which also modifies the viscosity and fluidness of themixture. Two monomer, benzyl methacrylate and 2-hydroxyethylmethacrylate, are applied in the mixture. Using the flexible nanoimprintmold, the results can be repeatable imprinting more than fifty timeswithout any contamination, the near zero residual of photoresistimprinting groove, smooth surface, vertical sidewall, 50 nm line-width,and 200 nm period patterns on flexible substrate ITO/PET film.

Nanoimprint Lithography (NIL)

Referring to FIGS. 5A to 5G, one embodiment of a method of NIL includes:

(S31) providing a substrate 30 and orderly forming a first sacrificelayer 310, a second sacrifice layer 320 and a resist 330 on thesubstrate 30;

(S32) providing a master stamp 20 with a nanopattern 208, pressing thenanopattern 208 into the resist 330, and forming a nanopattern 308 inthe resist 330; and

(S33) transferring the nanopattern 308 to the substrate 30.

Step (S31) further includes substeps of:

(S311) depositing the first sacrifice layer 310 on a top surface of thesubstrate 30;

(S312) forming the second sacrifice layer 320 covering the firstsacrifice layer 310; and

(S313) coating the resist 330 on a top surface of the second sacrificelayer 320.

In step (S311), the substrate 30 can be a flexible or rigid flat plate.The shape and size of the substrate 30 is not limited and can beprepared according to actual needs. The substrate 30 can be made offlexible polymer materials, such as silicone rubber, polyurethane, epoxyresin, and polyethylene terephthalate (PET). The substrate 30 can alsobe made of a rigid material, such as silicon dioxide, silicon, quartz,and glass diboride. A material of the first sacrifice layer 310 can bemade of a thermoplastic polymer, such as polymethyl methacrylate (PMMA),epoxy resin, unsaturated polyester resins and silicon ether resin. Inone embodiment, the substrate 30 is made of silicon, the material of thefirst sacrifice layer 310 is PMMA.

The first sacrifice layer 310 can be formed through any appropriatetechnique such as screen printing and spin casting. The first sacrificelayer 310 has a thickness ranging from about 100 nanometers to about 300nanometers. In one embodiment, the first sacrifice layer 310 is formedvia spin casting. The spin-coating speed is in a range from about 5400Round Per minute (RPM) to about 7000 RPM, the time is from about 0.5minutes to about 1.5 minutes. The first sacrifice layer 310 can be bakedabout 3 to 5 minutes at a temperature of about 140° C. to 180° C.

In step (S312), the second sacrifice layer 320 can be made of metal,such as aluminum (Al) or cesium (Cr), and can be formed viaelectron-beam evaporation, sputtering or chemical vapor deposition. Inone embodiment, the second sacrifice layer 320 is made of Al, anddeposited on the top surface of the first sacrifice layer 310 viaelectron-beam evaporation. The evaporation speed is in a range fromabout 0.5 angstrom/minute (A/min) to about 1.5 angstrom/minute (A/min).A thickness of the second sacrifice layer 320 is in a range from about30 nanometers to about 50 nanometers.

In step (S313), the resist 330 can be the nanoimprint resist used inP-NIL or T-NIL described above. The resist 330 can be deposited on a topsurface of the second sacrifice layer 320 via screen printing or spincoating. The resist 330 may have a thickness ranging from about 100nanometers to about 300 nanometers. In one embodiment, resist 330 isdeposited via spin casting. The spin-coating speed is in a range fromabout 5400 Round Per minute (RPM) to about 7000 RPM, the time is fromabout 0.5 minutes to about 1.5 minutes. The resist 330 can be bakedabout 3 to 5 minutes at a temperature of about 140° C. to about 180° C.

The step (S32) includes substeps of:

(S321) compressing the master stamp 20 with the substrate 30 to pressthe nanopattern 208 into the resist 330; and

(S322) curing the resist 330, and separating the master stamp 20 fromthe substrate 30 to form a nanopattern 308 in the resist 330.

In step (S321), the master stamp 20 is placed on the resist 330. Step(S321) can be performed in a vacuum environment to make sure the resist330 can be fully filled into the entire gaps 26 of the master stamp 20.In one embodiment, the step (S321) is performed in a nanoimprintingmachine. A vacuum of the nanoimprinting machine is 5.0E-03 millibar(mbar), after maintaining a pressure of about 12 pound/square inch (Psi)to about 15 Psi for about 5 to 10 minutes, the master stamp 20 ispressed into the resist 330, allowing the resist 330 filled with thegaps 26 of the master stamp 20.

In one embodiment, the resist 330 in step (S322) is the nanoimprintresist used in P-NIL descried above, and is cured via UV light andbecomes solid. The UV curing is performed with a energy flux density ofabout 10 mJ*cm⁻² to about 17 mJ*cm⁻², an irradiating time of about 10min to about 20 min, a vacuum of about 5.0E-03 mbar, and a pressure ofabout 50 Psi.

In another embodiment, the resist 330 in step (S322) is the nanoimprintresist used in T-NIL described above, and is cured via heating andbecomes solid. The step (S322) can also be performed in a nanoimprintingmachine. A temperature of the nanoimprinting machine can be in a rangefrom about 45° C. to about 75° C. before pressing. A vacuum of the nanoimprinting machine can be about 5.0E-03 millibar (mbar), aftermaintaining a pressure of about 12 pound/square inch (Psi) to about 15Psi for about 5 to 10 minutes, the master stamp 20 can be pressed intothe resist 330, allowing the resist 330 fully filled with the gaps 26 ofthe master stamp 20.

Referring to FIG. 5C, after separating the master stamp 20 from thesubstrate 30, a plurality of protrusions 304 and recesses 306 areexposed. Each protrusion 304 corresponds to one gap 26 of the masterstamp 20. The recesses 306 form reliefs which conform generally to theshape of the projecting portions 24 and the master stamp 20. Theplurality of protrusions 304 and recesses 306 form the nanopattern 308.It is easy to be understood that there may be remains (not shown) ofresist 330 at the bottom of the recesses 306 after the step (S322).

In step (S33), the transferring process can be performed via etchingmethod, step (S33) includes substeps of:

(S331) removing the remains of the resist 330 at the bottom of therecesses 306 to expose the second sacrifice layer 320 in part;

(S332) etching the second sacrifice layer 320 exposed by the recesses306 to expose the first sacrifice layer 310 in part;

(S333) etching the first sacrifice layer 310 exposed by the recesses 306to expose the substrate 30 in part; and

(S334) etching the substrate 30 exposed by the recesses 306.

In step (S331), the remains of the resist 330 at the bottom of therecesses 306 can be removed via oxide plasma etching. In one embodiment,the substrate 30 is placed into a microwave induced plasma (MIP) deviceto etch the remains of the resist 330 at the bottom of the recesses 306.An induction power source of the MIP device emits oxide plasma. Theoxide plasma has low ion power and etches the resist 330 for about 2minutes to about 8 minutes, whereby, the remains of the resist 330 isetched and a portion of the second sacrifice layer 320 is exposed by therecesses 306. In one embodiment, the power of the MIP device is 60 W andthe speed of the oxide plasma is 40 sccm (standard-sate cubic centimeterper minute). The partial pressure of the oxide plasma is 2 Pa.

In step (S332), the second sacrifice layer 320 exposed by the recesses306 can be removed via ion etching method. In one embodiment, thesubstrate 30 is placed into an inductively coupled plasma device, havinga mixture of oxygen and chlorine to etch the second sacrifice layer 320exposed by the recesses 306. In one embodiment, the power of theinductively coupled plasma device is 50 W, the speed of the chlorine is24 sccm, and the speed of the silicon tetrachloride is 24 sccm. Thepartial pressure of the silicon tetrachloride and chlorine is 2 Pa.

In step (S332), in another embodiment, the substrate 30 is placed into asolution of K₃[Fe(CN)₆] with a molality from about 0.06 mol/l to aboutmol/l, for about 4 to 15 minutes. The second sacrifice layer 320,exposed by the recesses 30, is removed by the solution of K₃[Fe(CN)₆].Thus first sacrifice layer 310 is partly exposed.

In one embodiment, the material of the second sacrifice layer 320 is Al,the step (S332) is performed via ion etching method. In someembodiments, the material of the second sacrifice layer 320 is Cr, thestep (S332) is performed via ion etching method or wet etching method.

In step (S333), the first sacrifice layer 310 exposed by the recesses 30is removed via oxide plasma etching, thus the substrate 30 is partlyexposed out of the recesses 306. The oxide plasma etching in step (S333)is similar to that of step (S331).

In step (S333), the substrate 30 exposed by the recesses 306 is removedvia reactive ion etching. In one embodiment, the substrate 30 placedinto an inductively coupled plasma device, with a mixture of silicontetrachloride and chlorine, to etch the exposed second semiconductorlayer 150, the active layer 140, and the first semiconductor layer 130.The power of the inductively coupled plasma device is 50 W, the speed ofthe chlorine is 26 sccm, and the speed of the silicon tetrachloride is 4sccm. The partial pressure of the silicon tetrachloride and chlorine is2 Pa.

In step (S333), referring to FIG. 5F, the residue of the first sacrificelayer 310 can be washed away, and thus the residue of the secondsacrifice layer 320, located on the residue of the first sacrifice layer310, can also be removed.

Referring to FIGS. 6A to 6D, one embodiment of a method of NIL includes:

(S41) providing a substrate 30 and forming a resist 330 on the substrate30;

(S42) providing a master stamp 20 with a nanopattern 208, pressing thenanopattern 208 into the resist 330, and forming a nanopattern 308 inthe resist 330; and

(S43) transferring the nanopattern 308 to the substrate 30.

Referring to FIG. 6A, in step (S41), the resist 330 can be directlycoated on the substrate 30 via a same method as that of step (S313). Theresist 330 has a thickness ranging from about 100 nanometers to about300 nanometers.

Referring to FIG. 6B, the step (S42) can be similar to step (S32).

In step (S43), the transferring process can be performed via etchingmethod, step (S43) includes substeps of:

(S431) removing the remains of the resist 330 at the bottom of therecesses 306 to expose the substrate 30 in part;

(S432) etching the substrate 30 exposed by the recesses 306.

Referring to FIGS. 7A to 7G, one embodiment of a method of NIL includes:

(S51) providing a substrate 30 and orderly forming a first sacrificelayer 310 and a second sacrifice layer 320 on the substrate 30;

(S52) providing a master stamp 20 with a nanopattern 208, and depositinga resist 330 on the nanopattern 208;

(S53) attaching the second sacrifice layer 320 to the resist 330,forming a nanopattern 308 in the resist 330; and

(S54) transferring the nanopattern 308 to the substrate 30.

The method of forming the first and second sacrifice layers 310, 320 onthe substrate 30 can be same as step (S31).

Step (S52) can be performed in a vacuum environment to make the polymercompound 110 can be fully filled entire gaps 26 of the master stamp 20.

The step (S53) includes substeps of:

(S531) compressing the master stamp 20 with the substrate 30 to pressthe nanopattern 208 into the resist 330, and attaching the secondsacrifice layer 320 to the resist 330;

(S532) curing the resist 330, separating the master stamp 20 from thesubstrate 30 to form a nanopattern 308 in the resist 330.

Depending on the embodiment, certain of the steps of methods describedmay be removed, others may be added, and the sequence of steps may bealtered. It is also to be understood that the above description and theclaims drawn to a method may include some indication in reference tocertain steps. However, the indication used is only to be viewed foridentification purposes and not as a suggestion as to an order for thesteps.

Finally, it is to be understood that the above-described embodiments areintended to illustrate rather than limit the disclosure. Variations maybe made to the embodiments without departing from the spirit of thedisclosure as claimed. The above-described embodiments illustrate thescope of the disclosure but do not restrict the scope of the disclosure.

1. A nanoimprint resist comprising: a hyperbranched polyurethaneoligomer (HP); a perfluoropolyether (PFPE); a methylmethacrylate (MMA);a diluent solvent; and a photo initiator.
 2. The nanoimprint resist ofclaim 1, wherein the HP is polymerized either by a copolymerization oftrimellitic anhydride, ethylene mercaptan, and epoxy acrylic acid, or bya ring-opening copolymerization epoxy acrylic acid and ethylene glycol.3. The nanoimprint resist of claim 2, wherein a chemical structure ofthe HP is:


4. The nanoimprint resist of claim 1, wherein the diluent solvent is2-hydroxyethyl methacrylate or 2-Hydroxy Ethyl 2-methyl ethylene.
 5. Thenanoimprint resist of claim 1, wherein in the nanoimprint resist, aweight percent of the HP is in a range from about 50 wt % to about 60 wt%, a weight percent of the PFPE is in a range from about 3 wt % to about5 wt %, a weight percent of the MMA is in a range from about 5 wt % toabout 10 wt %, a weight percent of the diluents solvent is in a rangefrom about 25 wt % to about 35 wt %, and a weight percent of the photoinitiator is in a range from about 0.1% to about 2%.
 6. The nanoimprintresist of claim 5, further comprising a polydimethlsiloxanes (PDMS) ormethacrylatesilane with a weight percent in a range from about 5% toabout 10%.
 7. A nanoimprint lithography method comprising: providing amaster stamp with a first nanopattern formed by a plurality ofprojecting portions and gaps and a substrate; forming a first sacrificelayer, a second sacrifice layer and a nanoimprint resist on thesubstrate, wherein the nanoimprint resist comprises a hyperbranchedpolyurethane oligomer (HP), a perfluoropolyether (PFPE), amethylmethacrylate (MMA), a diluent solvent and a photo initiator;pressing the first nanopattern into the nanoimprint resist, and forminga second nanopattern in the nanoimprint resist; and transferring thesecond nanopattern to the substrate.
 8. The method of claim 7, whereinthe HP is polymerized by a copolymerization of trimellitic anhydride,ethylene mercaptan, and epoxy acrylic acid, or polymerized by aring-opening copolymerization epoxy acrylic acid and ethylene glycol. 9.The method of claim 8, wherein a chemical structure of the HP is:


10. The method of claim 7, wherein the diluent solvent is 2-hydroxyethylmethacrylate or 2-Hydroxy Ethyl 2-methyl ethylene.
 11. The method ofclaim 7, wherein in the nanoimprint resist, a weight percent of the HPis in a range from about 50 wt % to about 60 wt %, a weight percent ofthe PFPE is in a range from about 3 wt % to about 5 wt %, a weightpercent of the MMA is in a range from about 5 wt % to about 10 wt %, aweight percent of the diluents solvent is in a range from about 25 wt %to about 35 wt %, and a weight percent of the photo initiator is in arange from about 0.1% to about 2%.
 12. The nanoimprint lithographymethod of claim 7, wherein the step of pressing the first nanopatterninto the nanoimprint resist, further comprises: compressing the masterstamp with the substrate to press the first nanopattern into thenanoimprint resist; and curing the nanoimprint resist, and separatingthe master stamp from the substrate to form a second nanopattern in thenanoimprint resist, the second nanopattern comprising a plurality ofprotrusions and recesses.
 13. The method of claim 12, wherein in step ofcuring the nanoimprint resist, the nanoimprint resist is cured via UVlight.
 14. The method of claim 12, wherein after separating the masterstamp from the substrate, there are remains of the nanoimprint resist inat least one of the recesses.
 15. The nanoimprint lithography method ofclaim 14, wherein the step of transferring the second nanopattern to thesubstrate. further comprises: removing the remains of the nanoimprintresist at the bottom of the recesses to expose the second sacrificelayer in part; etching the second sacrifice layer exposed by therecesses to expose the first sacrifice layer in part; etching the firstsacrifice layer exposed by the recesses to expose the substrate in part;and etching the substrate exposed by the recesses.
 16. A nanoimprintlithography method comprising the steps of: providing a master stampwith a first nanopattern and a substrate; forming a first sacrificelayer and a second sacrifice layer on the substrate; depositing ananoimprint resist on the first nanopattern, the nanoimprint resistcomprising a hyperbranched polyurethane oligomer (HP), aperfluoropolyether (PFPE); a methylmethacrylate (MMA), a diluent solventand a photo initiator; attaching the second sacrifice layer to thenanoimprint resist, forming a second nanopattern in the nanoimprintresist; and transferring the second nanopattern to the substrate. 17.The method of claim 16, wherein the HP is polymerized by acopolymerization of trimellitic anhydride, ethylene mercaptan, and epoxyacrylic acid, or polymerized by a ring-opening copolymerization epoxyacrylic acid and ethylene glycol.
 18. The method of claim 17, wherein achemical structure of the HP is:


19. The method of claim 16, wherein the diluent solvent is2-hydroxyethyl methacrylate or 2-Hydroxy Ethyl 2-methyl ethylene. 20.The method of claim 16, wherein in the nanoimprint resist, a weightpercent of the HP is in a range from about 50 wt % to about 60 wt %, aweight percent of the PFPE is in a range from about 3 wt % to about 5 wt%, a weight percent of the MMA is in a range from about 5 wt % to about10 wt %, a weight percent of the diluents solvent is in a range fromabout 25 wt % to about 35 wt %, and a weight percent of the photoinitiator is in a range from about 0.1% to about 2%.